Without knowing anything about your system, I offer the following:
My wife, about a week ago, did something to my pc that could only be described as fluffied up. I'm pretty sure it was spyware. I got rid of the spyware ok, but when I tried to start AH, I got the same result as you are having. What I did, was back up my settings, skins, and sounds folders, and did an uninstall/fresh install on AH. That was all it needed. I'm guessing that whatever she did, or my fix for it, screwed up AH.
Worth a shot anyway.